In the case of a reciprocal engine (internal combustion engine) for automobiles, for the purpose of improving measures against engine exhaust gas and reducing pumping loss, a variable valve device is more and more often installed in its cylinder head.
In some of such variable valve devices, an inner camshaft is turnably encased in an outer camshaft formed of a pipe member to function as a shaft member driven by crank output of the engine. In the outer periphery of the outer camshaft, there are provided a fixed reference cam and a movable cam that is turnable around the shaft axis. A pin-like member that is inserted in between the movable cam and the inner camshaft from a shaft-diametrical direction is used to connect the outer camshaft and the inner camshaft while allowing relative displacement. Due to this structure, the inner camshaft is relatively displaced by output of the outer camshaft, and the movable cam is varied in phase relative to the reference cam by output from the pin-like member connected to the inner camshaft, to thereby change the duration for which the valve is open (split variable) (see Patent Documents 1 and 2).
In the variable valve device, it is required to connect the inner camshaft and the movable cam, which are located in the inside and outside, respectively, of the outer camshaft with simple work. To that end, it has been proposed that a press-fit pin be used as the pin-like member for connecting the movable cam and the inner camshaft, and that the press-fit pin be pressed in along the shaft-diametrical direction to connect the movable cam and the inner camshaft located in the inside and outside, respectively, of the outer camshaft. It has also been proposed that a bolt member be used as the pin-like member, and that this bolt member be screwed into the inner camshaft to connect the movable cam and the inner camshaft located in the inside and outside, respectively, of the outer camshaft.